In order to raise and lower window panes in motor vehicles electro-motorized window lifters are known which are suitable for installing in the doors of motor vehicles and which have a drive device in the form of for example an electric motor with attached gearing or gear motor which can be connected to a vehicle battery through a wiring connection and switch.
The window pane which can be raised or lowered in the vehicle door through the electro-motorized window lifter is thereby fixed along its lower edge to a guide slide which can be moved up and down along a profiled rail by means of for example a closed cable loop. The cable loop runs around a cable drum which is driven for example through a worm gearing of the electric motor in a compact drive device which can have a cable drum in addition to the electric motor and worm gearing and which is fixed on the supporting parts of the inside of the vehicle door, for example a support plate, in the same way as the profiled rail.
As an alternative to this the drive device can be used to operate a cross-arm window lifter or other adjustment devices in the motor vehicle, for example a a horizontal seat adjuster.
Since different forces are required to raise and lower the window pane the electric motor is connected to a control device, a control and regulating circuit which is connected to a sensor of a measuring system for determining the speed or position of the electric motor. The control device for raising or lowering the window pane is controlled by the vehicle driver or passenger who operates the control switch.
From DE 198 51 455 A1 an electronics module is known for a drive unit which is operated by an electric motor. The electronic components are soldered onto a small plate in an electronics housing part. To control the drive unit a relay is used to switch on the current supply to the motor.
In EP 0 474 904 an electronics module as previously described is integrated in a gear housing. Also here a relay is switched on to control the current supply to the electric motor.
For future window lifter systems the torque or rotational speed of the electro-mechanical drive device is regulated through a control device. Regulation of this kind is known from DE 198 23 376 A1 where the semi-conductor circuit is provided with a semi-conductor bridging circuit. A semi-conductor bridging circuit generally uses four power directions of rotation.
If the power semi-conductors are arranged in a thermally poor conducting environment then the power semi-conductors have to be safeguarded against thermal overload. If the temperature in the power semi-conductor is too high then for example a surge breakthrough can lead to destruction of the structural element. In order to keep heating of the power semi-conductor as low as possible the switch-on resistance must be restricted for example through the parallel circuit connection of several transistors. For small switch-on resistances however correspondingly large transistor matrices are required, with the correspondingly large amounts of silicon which are necessary.